Question

Two bar magnets are placed on a smooth surface with their north and south poles facing each other. A student measures the force between the magnets as they move them farther apart from each other. The results are shown in the table.



Distance Between Magnets (cm) Strength of Magnetic Force (arbitrary units)
1.0 100
2.0 25
4.0 6
6.0 3




As the distance between the magnets increases, the magnetic force
Choose...
because
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.

Answer 1

As the distance between the magnets increases, the magnetic force decreases because it is (approximately) inversely proportional to the square of the distance (F ∝ 1/r^2). For example, doubling the distance (1 → 2 cm) reduces the force to 1/4 (100 → 25), and the values at 4 and 6 cm closely follow 100/(4^2) ≈ 6.25 and 100/(6^2) ≈ 2.78.